Of the 69 practices contacted, 14 (20%) agreed to participate. As one practice had only recently started using the PHQ-9, and the number of patients identified (n = 4) was too low for inclusion, data were extracted from the medical records of 13 of the 14 practices. Of the participating practices, nine were in Wiltshire PCT, two in Southampton City PCT, and two in Hampshire PCT. The total list size for all practices that were included was 77 820 (ranging from 3000–15 000 registered patients). The incidence of depression for the QOF year 2010 ranged from 0.3% to 1.5% and, on average, 79% of patients who were eligible for a second PHQ-9 assessment were followed up in accordance with the DEP 3 indicator (ranging from 23% to 100% across practices).
Anonymised data were extracted from 608 patients with a record of two valid PHQ-9 scores in the agreed time frame. Four patients scored below the lower cut-off point of five on the PHQ-9 and, hence, were excluded; this left a final sample of 604 patients.
The mean age of the sample was 44.4 years. In total, 418 (69%) patients were female and 216 (36%) had a previous history of depression. One or more comorbidities were present in 106 (18%) patients of the population; 15 (2%) had two comorbidities. No patients were identified as having >3 comorbidities. Using χ2 tests, no significant differences were observed with regard to treatment response between males and females, those with prior history of depression, or those with comorbidity.
Of the sample, 421 (70%) patients had a follow-up appointment within 4 weeks; the mean number of follow-up appointments in the first 12 weeks was 3.5, and 1.2 in weeks 13–26. The majority of the participants were treated with antidepressant medication — 572 (95%) received at least one drug prescription in the first 16 weeks — and 129 (21%) were referred for a mental health appointment within 16 weeks of diagnosis.
The majority of the sample (95%, n = 576) satisfied the case threshold for depression at the initial assessment, whereas, at follow-up, the number reaching case threshold fell to 318 (53%). At follow-up, 379 (63%) showed an adequate treatment response, 97 (16%) a borderline response, and 128 (21%) an inadequate response, according to the specified definition. illustrates the frequency of the absolute changes observed between patients’ first and second PHQ-9 scores.
A frequency histogram illustrating the absolute change in PHQ-9 score observed between the first and second scores recorded.
The second PHQ-9 was administered, on average, 54 days after the first. As the median time between the two was 52 days (interquartile range [IQR] 42–64), on average the second PHQ-9 was completed 7–8 weeks after the first. In 95% of cases, the second PHQ-9 questionnaire was done within 12 weeks of the first and rarely in <35 days (5 weeks, range 5–118 days). shows the time between first and second PHQ-9 questionnaires being done in days.
A frequency histogram illustrating the recorded time between the first and second of the PHQ-9 pairs.
A management change was recorded in 308 (51%) patients in the 26 weeks of observation following the first PHQ-9 score; 129 (21%) of the total study sample experienced at least one referral, 160 (26%) one drug change, and 118 (20%) at least one dose change. Management changes within 4 weeks of the follow-up PHQ-9 being completed were observed in 119 (20%) patients; these consisted of referral (5%), change in drug (14%), and change in dose (8%), with 20 (3%) patients experiencing >1 management change. On average, the relevant management change following the second PHQ-9 was made after 9 days. However, this mean figure is somewhat skewed by a few changes that were made a considerable time after the PHQ-9 questionnaire was given out.
The median time to treatment change was 0 days — that is, the treatment changes were made on the day that the PHQ-9 was administered. In fact, 87% of changes were made on the same day as the second PHQ-9 and 95% were made within 8 weeks. The majority of changes were made on the same day in all groups: adequate 92%, borderline 84%, and inadequate 76%. Only management changes recorded in the 4 weeks following the second PHQ-9 were included in the subsequent analysis.
Results from the logistic regression, controlling for baseline factors, demonstrated a relationship between the change in PHQ-9 score and management change — for each 1-point increase in the absolute difference between the first and second PHQ-9 scores, the odds of experiencing a management change were reduced by about 12% (). Patients who showed an inadequate response in score change at the time of second assessment were nearly five times as likely to experience a management change in the 4 weeks following the second assessment ().
The odds of experiencing a management change in relation to the absolute score change between the first and second PHQ-9 scores.a
Odds ratios of experiencing a management change in the 4 weeks following the second depression measure
Similar findings were observed when examining caseness following the second PHQ-9 measure. Looking at those patients who were classified as a case at baseline, those remaining above the case threshold were more than six times more likely to experience a management change in the 4 weeks following the second assessment, compared with those who fell below the threshold ().
Odds ratios for experiencing a management change in the 4 weeks following the second depression measure according to case or non-case status
The analysis was repeated, recategorising those with borderline response using treatment response defined as PHQ-9 <10 (adequate) versus PHQ-9 ≥10 (inadequate). Those with an inadequate response were still nearly five times more likely to experience a management change in the 4 weeks following the second assessment ().
Odds ratios of experiencing a management change in the 4 weeks following the second depression measure according to treatment response if a borderline response is recategorised according to case status
All regression analyses controlled for baseline factors, including a prior history of depression and comorbid physical illness. Compared with those patients who had no comorbid condition, those who had a comorbid condition were no more likely to experience a treatment change (adjusted odds ratio 1.11; 95% confidence interval [CI] = 0.41 to 3.14). However those with a previous history of depression were 1.59 times (95% CI = 1.11 to 2.28) more likely to have a treatment change. Looking only at the subgroups, including those with comorbid illness or prior history of depression, the observed relationship between inadequate treatment change and management change still held (data not shown)